The present invention relates to the supply of fibers to the spinning chamber of an open end spinning device and in particular to a method and apparatus for directing the flow of fibers so that the fibers are uniformly oriented on the collecting surface.
Conventional open end spinning units comprise a rotatable turbine having a rear wall and a continuous radially inwardly inclined side wall forming a cuplike chamber and defining a fiber collecting surface. Fibers are fed to the chamber through a duct or passage, formed in a supporting body, after being separated from a continuous roving or string. The fibers are centrifugally flung onto the collecting surface and the yarn is withdrawn in a path along the axis rotation of the chamber.
The direction of the fibers into the collecting surface may be obtained by positioning the opening or mouth of the feed duct or channel adjacent the side wall and by directing the opening in line with the collecting surface or by providing separator or divider means interposed between the end of the channel and the chamber. In either instance, it is helpful to allow the fibers to slide over the side wall, since a twofold benefit might be obtained. On the one hand, it serves to maintain separation of the infeed fibers from the spun yarn as the yarn is being withdrawn, and on the other hand, it provides a straightening of the fibers by their frictional action in sliding on the inclined surface. This latter action is supplemented by the cooperative flow of air through the duct and chamber which also serves to accelerate the fibers leaving the duct and entering the chamber.
In any event, the known spinning units, whether using a separate divider as a directing means or not, have the defect in that the fibers actually entering the chamber are not uniformly directed or oriented but are in fact heterogeneously flung into the chamber in an uncontrolled state, being further acted upon by the adverse frictional engagement with the side wall over which they slide. A second defect lies in the fact that the acceleration of the fibers during their passage from the duct into the chamber, by the action of the air flow, further causes the fibers to slide on the inclined side wall in an uncontrolled and unbraked condition.
The foregoing defects have serious consequences in the formation of the yarn, since the operational characteristics of rotary spinning chambers depend substantially upon an even distribution and straightening of the fibers on to the collecting surface. The straightening of the fibers has a decisive influence on the ultimate strength and tensil property of the obtained yarn. The more the fibers on the collecting surface of the spinning chamber are straightened, the easier the fibers may be spun and twisted into the yarn ribbon. In addition to strengthening the yarn thus produced, the easier the fibers are twisted into the yarn ribbon, the fewer the number of yarn breakages during the spinning process. It has been generally accepted that yarns made in the rotating spinning chamber of open end spinning machines are of lower strength than yarns made of the same material in conventional ring spinning machines. It has also been accepted that the fibers in the yarn which is made in open end spinning machines are more creased, i.e.: curled, and therefore of relatively shorter length than the same fibers spun into yarn by other methods.
It is the prime object of the present invention to overcome the disadvantages and defects of the prior art as enumerated above and provide a yarn, made by the open end spinning process, which has comparable strength and longer length fibers to those made in other processes.
The prime reason for the enumerated disadvantages inherent in open end spinning units consists in the low efficiency of the frictional force created between the fiber and the sliding wall of the spinning chamber, for straightening of the fibers. Fibers deposited on the inclined wall are subjected to the action of centrifugal forces which are greater than the frictional forces so that the fibers are quickly accelerated to a circumferential speed which approaches the circumferential speed of the collecting surface and which cause the fibers to quickly slide on the inclined wall onto the collecting surface. The fibers form a fibrous ribbon which is twisted by the action of rotation of the spinning chamber and which becomes wrapped on to the end of the already finished yarn, thus forming the continuous yarn without the individual fibers becoming straightened.
In the known conventional spinning units the fibers are deposited on the side wall of the rotating spinning chamber, which is usually of conical shape so that both the front and the rear ends of the fiber are deposited along approximately the same diametrical line of the inclined side wall, i.e.: on a certain contour plane parallel to the collecting surface of the spinning chamber. Thus, a centrifugal force acts uniformly on the entire length of the fiber, the force being equal value at both the front and rear end of the fiber. Thus, it depends solely on random conditions and random influences as to which of the fiber ends is to be accelerated with a greater force in the direction of the circumferential speed of the spinning chamber. The effect of a higher acceleration on the front end of the fiber is favorable since it will tend to straighten the fiber. However, in the opposite case, that is the effect of the higher acceleration on the rear end of the fiber, an undesirable curling and creasing of the fiber occurs and the fiber is deposited in an undesireable condition on the collecting surface. As a result of this latter condition, the phenomena, previously mentioned, occurs, having very unfavorable influence upon the property of the yarn being manufactured.
Because centrifugal forces act on both the front and rear end of the fibers simultaneously, the deposition of the fibers on the inclined wall, without first directing and orienting them with respect to their flow path, results in a nonuniform movement of the fibers in the radial direction on the inclined side wall. That is, the fibers move randomly in a nonuniform curve on the inclined surface toward the collecting surface.
The deposition of fibers on to the inclined or side wall, without orientation or proper direction, results in the movement of the individual fibers heterogeneously and in random manner, in the radial direction over the side wall, i.e.: in a spiral curve, toward the collecting surface. Thus, which end of the fiber is actually deposited first on the collecting surface depends upon the local and random conditions on the portion of the slide wall with which the fiber first makes contact. Such conditions as the surface roughness, its contamination with dirt, and flow of actual air over the surface are factors entering into the movement of the fibers. At the moment the fibers are deposited onto the collecting surface, the fiber has as yet not accelerated by the frictional forces acting between it and the inclined surface so as to attain the circumferential speed of the collecting surface. It only asymptotically approximates such speed. The collecting surface has frictional properties which are completely different from those of the inclined sliding wall, particularly because of the accumulation of dust and impurities thereon. A substantial influence upon the collection of the fibers on the collecting surface is also exerted by the existence of any incomplete ribbon or yarn remaining on the collecting surface.
When the front end of the fibers reach the collecting surface first, an intensive circumferential acceleration takes place by action of an increased entraining force, causing a straightening of the fibers at the moment at which it is deposited on the collecting surface. However, when the fiber reaches the collecting surface with its rear end first, as a result of the above indicated random influences and conditions, then the fiber is undesireably creased and curled onto the collecting surface, resulting in the detailed defects in the formation of the yarn ribbon as mentioned above.
It is the object of the present invention to provide an improved open end spinning process in which yarn is produced having greater strength and thereby increase the utility and application.
It is a further object of the present invention to improve the control and movement of fiber flow from the feed channel into the spinning chamber so that the fibers are deposited onto the collecting surface with a greater degree of orientation and direction then heretofore so as to provide a more uniform continuous yarn.
It is a further particular object of the present invention to achieve a control in the straightening and in the direction of the fibers with respect to their flow path, and near to the collecting surface as is possible. In contrast with other systems wherein which it was attempted to straighten the fibers in an early stage of their flow path, as for example within the feed channel or at the time the fibers are torn from the roving, the present invention intends to effect the straightening and orientation as close to the collecting surface as possible. In the contrasted systems, the fibers would still have to overcome a rather long space or distance between the time they are straightened and the time they reach the spinning chamber. Thus, the danger of creasing or curling the fibers due to local conditions, e.g. frictional engagement with the wall of the feed channel, would still exist. According to the present invention the fiber is acted upon immediately before entering the spinning chamber, and at that point the direction of the movement of the fiber is changed and a sufficient inertia is applied to provide the desired result. Further, upon entering the spinning chamber, the character of the air flow in which the fibers are borne, is radically changed since the fibers, after leaving the feed channel, are subdued and subsidiary to the intensive action of a transverse flow of air, caused by the rotation of the spinning chamber. As a result, the fiber would impact or, come into contact with the inclined wall of the spinning chamber whereon because of the friction between the fiber and the side wall the velocity of the fibers is considerably increased, prior to deposition on the collecting surface.
In those constructions wherein the open end spinning unit is provided with a dividing means between it and the feed channel, the fiber is intended, according to the present invention, to be directed onto the inclined wall of the spinning chamber after first engaging the dividing means. In this manner it is possible to influence the fiber to such a degree as to achieve straightening at this point, thus making it possible for the fiber to reach the collecting surface of the spinning chamber in a high degree of orientation and straightness.
The present invention is therefore directed to the method and apparatus for achieving a controlled inlet of the fibers onto the sliding wall of the spinning chamber and for straightening the fibers to a maximum degree so that they may be subsequently deposited in this condition onto the collecting surface. As a result, yarn of higher quality will be attained.
The foregoing objects, and advantages, together with numerous other objects and advantages will be seen and appreciated from the following description of the present invention and the means for carrying the present invention into practice.